Heat transfer to a horizontal disc using a buoyancy-induced jet

Abstract

A study of the buoyancy-induced flow from a hot vertical tube impinging on a cold horizontal disc has been carried out. This geometry is analogous to a single pan biomass stove, with a vertical tube followed by a horizontal radial diffuser. Flow visualization experiments have been conducted to observe the flow in the diffuser. These visualizations show a recirculation zone at the entrance of the diffuser whose size depends on the diffuser spacing. A numerical simulation of the system has been carried out using a finite difference technique to study the dependence of fluid flow and heat transfer on Grashof number and the geometrical parameters. The details of the buoyancy induced flow structure are elucidated. The size of recirculation zone and the flow pattern in the diffuser predicted by the calculations is similar to those observed in experiments. The spacing between the diffuser discs is found to have a strong influence on the flow pattern, mass flow and heat transfer to the horizontal disc. The outer radius of the diffuser mainly affects the total heat transfer to the disc.